1 Introduction

Geochemical studies of clastic sedimentary rocks reveal the source area, tectonic setting of the basin and in addition provides insights into the paleogeographic, chemical environment of deposition (Bhatia and Crook 1986; Roser and Korsch 1986, 1988; Erickson et al. 1992; Cullers and Podkovyrov 2000; Condie et al. 2001; Absar et al. 2009, 2016; Khan and Khan 2015, 2016) and helps to estimate weathering intensity and paleoclimate (Bhatia 1983; Bhatia and Crook 1986; Roser and Korsch 1986, 1988; McLennan et al. 1990). The geological processes leave characteristics in the form of geochemical signatures making sedimentary rocks as the most important repository of geochemical data available for the reconstruction of ancient earth surface environment (Sageman and Lyons 2005). Petrography, which includes modal abundances of minerals and textural analysis, is important; however, due to some inherent advantages of geochemistry later became a valuable tool. Studies of major oxides, selected trace elements and rare earth elements (REEs) including LREE and HREE and their ratios are sensitive indicators for provenance and tectonic settings (Bhatia 1983; Bhatia and Crook 1986; Roser and Korsch 1986, 1988; McLennan and Taylor 1991; Condie 1993; Nesbitt and Young 1996; Cullers and Podkovyrov 2002). The La and Th are immobile elements and are found in higher proportion in felsic source whereas, concentration of trace elements like Co and Sc are higher in mafic igneous source (Taylor and McLennan 1985; Wronkiewicz and Condie 1987). Therefore, higher values of Th/Sc, Th/Co and La/Sc display crustal derivation and lower values indicate a mantle source. The aim of this study is to estimate the geochemical discriminations among two different formations of Chitravati Group of Cuddapah Supergroup and to understand their source characteristics, paleoclimatic conditions and tectonic setting.

Fig. 1
figure 1

Generalised geological map of Papaghni sub-basin showing various formations of Papaghni and Chitravati Groups. Sample locations are marked (modified after Saha and Tripathy 2012).

Full size image

2 General geology of study area

The crescent-shaped intra-cratonic Cuddapah basin extends for about 440 km in length along its eastern margin and 145 km diagonally in its widest part (Nagaraja Rao et al. 1987). It is a foreland basin in front of the Eastern Ghat Mobile Belt (EGMB; Dasgupta et al. 2005; Saha and Patranabis-Deb 2014; Matin 2015). Cuddapah sediments rest on the Archeans (\(\sim \)2520 Ma; Jayananda et al. 2008) and many of the schist belts also form basement (i.e., Veligallu, Kadiri, Penakacherla, Gadwal, etc., King 1872; Nagaraja Rao et al. 1987; figure 1). The grade of metamorphism increases from west to east during the Middle to Late Proterozoic Eastern Ghat Orogeny (Goodwin 1996). The Cuddapah basin contains sedimentary piles belonging to Paleo-Mesoproterozoic Cuddapah Supergroup and Meso-Neoproterozoic Kurnool Group. A major unconformity separates the Cuddapah Supergroup from the overlying Kurnool Group. The Cuddapah Supergroup consists of Papaghni, Chitravati, Nallamalai groups and Srisailam Quartzite. All these units are separated by the unconformities which show variable environment of deposition (Saha and Tripathy 2012; figure 2). Kurnool Group is followed by Banganpalli Quartzite, Narji Limestone, Owk Shale, Paniam Quartzite, Koilkuntla Limestone, and Nandyal Shale. On the basis of sediment characteristics, spatial distribution and evolution of the basin through time, Nagaraja Rao et al. (1987) identified four sub-basins within the Cuddapah Basin (Papaghni sub-basin, Kurnool sub-basin, Srisailam sub-basin and Palnad sub-basin). Papaghni sub-basin consists of Papaghni and Chitravati Group. Papaghni Group consists of Gulcheru and Vempalle formations. Gulcheru Formation comprises conglomerate and quartzite (figure 2) (\(2502\,\pm \,17\,\hbox {Ma}\); Nagaraja Rao et al. 1987; Chakrabarti et al. 2009; Basu et al. 2014; Collins et al. 2015) and Vempalle Formation is predominantly carbonate succession containing dolomites (\(1752\,\pm \,41\,\hbox {Ma}\); Zachariah et al. 1999), shale, quartz arenite, chert, basic flows and sills. Basal unit of dolostones are uranium-bearing dolomites/calcareous arenite, forms part of the Vempalle Formation (Absar et al. 2016, reference therein). Chitravati Group, disconformably overlies the Papaghni Group, which is comprised of alternate sequences of arenaceous, argillaceous lithounits, basic sills and tuffs. These lithounits together form Pulivendla Quartzite, Tadpatri Formation and Gandikota Quartzite (Nagaraja Rao et al. 1987). In Chitravati Group, the basal sedimentary unit is thin persistent bed of conglomerate with jasper/oolitic chert, quartz, and quartzite, which is traversed by quartz veins. The east–west trending thin persistent (\(\sim \)50 m) Pulivendla Quartzite (\(1923\pm 22\,\hbox {Ma}\); Collins et al. 2015) starts with a chert pebble conglomerate and quartzite sequence. It is exposed mainly at Thallapalli (\(14^{^{\circ }}22^{\prime }38.8^{\prime \prime }\)N, \(78^{^{\circ }}23^{\prime }36.7^{\prime \prime }\)E), Rajupalem (\(14^{^{\circ }}26^{\prime }20.7^{\prime \prime }\)N, \(78^{^{\circ }}29^{\prime }30.9^{\prime \prime }\)E) areas on eastern side and Lingala (\(14^{^{\circ }}30^{\prime }01.0^{\prime \prime }\)N, \(78^{^{\circ }}06^{\prime }21.3^{\prime \prime }\)E), Velidandla (\(14^{^{\circ }}32^{\prime }46.0^{\prime \prime }\)N, \(78^{^{\circ }}03^{\prime }13.5^{\prime \prime }\)E) areas on the northwest side of Pulivendla town with gentle dip along the NE–SW strike. In the Mustukota (\(14^{^{\circ }}50^{\prime }34.9^{\prime \prime }\)N, \(77^{^{\circ }}52^{\prime }23.9^{\prime \prime }\)E) area, the quartzites are exposed with symmetrical ripple marks (figure 3a).

Fig. 2
figure 2

Stratigraphic litholog (not to scale) of Cuddapah Supergroup (after Nagaraja Rao et al. 1987; Anand et al. 2003).

Full size image
Fig. 3
figure 3

Field photographs of Pulivendla and Gandikota Quartzite. (a) Ripple marks on Pulivendla Quartzite together symmetric and asymmetric ripples are present. (b) Herring bone crossbedding of Gandikota Quartzite. (c) Symmetrical ripples on Pulivendla Quartzite with Chert pebbles. (d) Graded bedding nature of massive quartzite with facies variations.

Full size image

The Pulivendla Quartzite is overlain by the thick Tadpatri Formation, which is comprised of shale, ash fall felsic tuffs (\(1862\pm 9\,\hbox {Ma}\); Sheppard et al. 2017a), intrusives (\(1885\pm 3\,\hbox {Ma}\); French et al. 2008; \(1899\pm 20\,\hbox {Ma}\); Anand et al. 2003); quartzite and dolomite. Gandikota Quartzite (\(1181\pm 29\,\hbox {Ma}\); Collins et al. 2015) is the topmost formation of the Chitravati Group, which has gradational contact with Tadpatri shale (Nagaraja Rao et al. 1987; Lakshminarayana et al. 2001). The sandstone–shale intercalations and medium to coarse grained quartz-arenite to feldspathic arenite represent the Gandikota Quartzite. It is geographically distributed mainly in the Gandikota hill range (\(14^{^{\circ }}47^{\prime }55.8^{\prime \prime }\)N, \(78^{^{\circ }}17^{\prime }00.3^{\prime \prime }\)E), Muddanuru to Jammalamadugu road section and Nossam (\(14^{^{\circ }}58^{\prime }15.0^{\prime \prime }\)N, \(78^{^{\circ }}22^{\prime }40.6^{\prime \prime }\)E), Kanakadri Palli (\(15^{^{\circ }}02^{\prime }45.3^{\prime \prime }\)N, \(78^{^{\circ }}03^{\prime }57.8^{\prime \prime }\)E) areas as inliers (Nagaraja Rao et al. 1987; Reddy et al. 1990). The nature of the beds in the Gandikota formation shows gentle (10–15\(^{^{\circ }}\)) dip with the outcrop pattern giving rise to a synclinal structure termed as Nawabpur syncline (Nagaraja Rao 1974). Herringbone cross bedding and ripple marks are the major primary sedimentary structures observed in these quartzites (figure 3b). Mainly two members of lithofacies of Gandikota Formation signify prograding shoreline depositional setting, a tide dominated shallow marine environment respectively (Lakshminarayana and Bhattacharjee 2000). Primary sedimentary structures, predominantly ripple marks are common in both Pulivendla and Gandikota formations (figure 3a and c). Six phases of contemporaneous igneous activity were reported in the form of basic sills, flows, ash fall tuffs and volcanic flows within Papaghni sub-basin (Sen and Narasimha Rao 1967; Sai 2014).

Nallamalai Group is composed of lower Bairenkonda Quartzite (Nagari), and upper Cumbum (Pullampet shale) Formation (Nagaraja Rao et al. 1987; Saha and Tripathy 2012). The Nallamalai Group is thrust over the lowest Papaghni, Chitravati groups and the uppermost Srisailam Formation and Kurnool Group of the Cuddapah Basin (Saha and Chakraborty 2003; Saha et al. 2010; Collins et al. 2015) along Rudravaram line (Saha et al. 2010) or major Maidukuru thrust (Meijerink et al. 1984; Patranabis-Deb et al. 2012). The Nallamalai Group consists of the lower Bairenkonda (Nagari) Formation, which is sandstone dominated and the upper Cumbum (Pullampeta) Formation consisting mainly of shales punctuated by sandstones and dolomites. The basal part of the Bairenkonda Formation was deposited between 1659 and 1590 Ma (Joy et al. 2015). The youngest age limit of the Nallamalai Group was constrained to be as \(\sim \)1400 Ma old, which is in the form of Chelima lamproite (intrusion in to the Cumbum Formation; Rao et al. 1996, 1999, 2012; Kumar et al. 2001). Pan-African overprint of 531 Ma was recently confirmed by dating monazite from low grade metamorphic black shales from Cumbum Formation at Mangampet barite mine region (Sheppard et al. 2017b).

3 Sampling and analytical techniques

For the purpose of petrography and geochemical studies, 41 representative samples of quartzites from Pulivendla and Gandikota formations of Chitravati Group were collected. At the time of sampling, care has been taken to select fresh rock samples. Thin sections for petrographic studies were prepared at Geochemistry Division, CSIR- National Geophysical Research Institute.

Fig. 4
figure 4

Microphotographs of Pulivendla Quartzite. (a) Pulivendla Quartzite showing monocrystalline well-rounded quartz (Qtz) with over growth, detrital Zircon grain (Zr) overlapping on monocrystalline quartz grain. Well-rounded quartz grains are replaced by chert grains (Ch). Moderate to well-rounded chert clasts in the form of cryptocrystalline to microcrystalline can be seen in the photomicrograph. (b) Elongated chert grain encircled by overgrowth quartz grains. Opaque minerals are showing dark colour (ppl). (c) Majority of well-rounded to subrounded chert grains surrounded by overgrowth quartz grains. quartz grains replaced by chert grains (Ch). (d) Well-rounded detrital Zircon enclosed by well-sorted monocrystalline quartz grains. (e) This photograph shows ooids with well-developed radial and concentric structures encircled by well-rounded quartz grains. (f) Pulivendla Quartzite showing subangular grains and are well sorted.

Full size image
Fig. 5
figure 5

Microphotographs of Gandikota Quartzite. (a) Subangular grains of feldspar and quartz are well sorted. Secondary overgrowth of silica (in optical continuity). A common feature of diagenesis (Xed) discontinuous lines showing original grain boundaries and silica overgrowth. (b) Quartz is the dominant framework grain; it is in the form of monocrystalline quartz (MQ), lesser content of polycrystaline quartz (PQ). Silica is the main cementing material. Monocrystalline quartz predominates over polycrystalline type. (c) Quartz grains showing concave contact at centre. An authigenic overgrowth on a detrital quartz grain arrow mark showing. Monocrystalline quartz (MQ) is common. (d) Angular feldspar grains with chert and opaque minerals. Fresh and unaltered microcline showing typical cross hatched (Tartan) twinning under Xed nicols. Chert (Ch) replaced the subrounded quartz grain. (e) Microcline and feldspar with opaque minerals. (f) Carbonate cementing (CC) material at centre of photograph with subangular to rounded quartz grains. Overgrowth of quartz grains showing optical continuity.

Full size image

Major elements have been analyzed by X-ray Fluorescence (XRF) spectrometer (Axios, PANalaytical) and trace elements have been analyzed using high resolution inductively coupled plasma mass spectrometer (HR-ICP-MS; Nu Instruments Attom, UK) at CSIR-National Geophysical Research Institute, Hyderabad. The precision, accuracy and the analytical protocols of the data are given by Krishna et al. (2007) and Satyanarayanan et al. (2014) for XRF and HR-ICP-MS, respectively.

4 Petrography

4.1 Pulivendla Quartzite

The Pulivendla Quartzite contains quartz as the main mineral, which is in detrital mode in the form of common quartz (monocrystalline quartz), polycrystalline quartz (recrystallised quartz and stretched metamorphic quartz; figure 4a) followed by feldspar in the form of K-feldspar (orthoclase and microcline) and plagioclase (figure 4f). Sericitization is observed in some sections. Mica is present in the form of biotite and muscovite. The rock fragments (siliceous oolites) and heavy minerals (zircon, apatite) are also present (figure 4d). The quartz grains are mainly fine to medium grained, well sorted and also contain subrounded to well-rounded grains (figure 4d) with secondary overgrowths (forming a quartz cement; figure 4b) in optical continuity with the clasts. The main cementing material is silica with lesser amount of carbonate. The resulting new grains (clasts plus their overgrowths) form a roughly polygonal aggregate. Some of the grain contacts are irregular to sutured (figure 4c). Chert grains showing oolitic (silicious) texture and are surrounded by well rounded quartz grains (figure 4e). Subangular to angular with well sorted quartz grains and microcline grains reflecting the textural immaturity of sediments (figure 4f).

Modal analysis of the Pulivendla Quartzite using point counting method reflecting the average quartz percentage in the form of monocrystalline and polycrystalline grains is about 92%, feldspar along with plagioclase and microcline is 4%, lithic fragments (including chert) and matrix is 1%. Based on Qt–F–L ternary diagram (Dickinson 1985; figure 6a), the Pulivendla Quartzite is plotted in the craton interior and recycled orogenic fields. Subsequently, the sandstone classification triangular diagram (Folk 1974; figure 6b) represents the Pulivendla Quartzite which are in the fields of sub-arkose, quartz-arenite, sub-litharenite.

4.2 Gandikota Quartzite

Gandikota Quartzite contains quartz as the main detrital mode in the form of common quartz with undulose extinction (monocrystalline), polycrystalline quartz (figure 5a and b) followed by K-feldspar (orthoclase and microcline) and plagioclase (figure 5d). Silica cement occurs in the form of overgrowth around quartz detrital grains (figure 5c). Mica is present in the form of muscovite and biotite. The thin sections of the Gandikota Quartzite show absence of rock fragments. K-feldspar is common and it is altered to sericite. Common cementing material is silica, calcite is also observed in some sections (figure 5f). Chlorite and sericite occur as the main matrix material. Heavy minerals like zircon are present in euhedral shape and in the form of inclusions in quartz grains as they are mostly of detrital origin.

Modal analysis of Gandikota Quartzite using the point counting method average quartz including monocrystalline and polycrystalline quartz is 86%, feldspar including plagioclase and microcline is 6% and the rock fragments (chert) are 6%. In the Qt–F–L ternary diagram, these samples plot in craton interior field and recycled orogenic field (Dickinson 1985; figure 6a). Further using the modal analysis for sandstone classification triangular diagram (Folk 1974; figure 6b), Gandikota Quartzite plot in the quartz-arenite, sub-arkose, and sub-litharenite field.

5 Results

5.1 Major oxides

Pulivendla Quartzite contains higher content of \(\hbox {SiO}_{2}\) (85.57–96.67, avg. 89.73) followed by lower proportion of \(\hbox {Al}_{2}\hbox {O}_{3 }\) (0.49–8.19, avg. 6.87), \(\hbox {TiO}_{2}\) (0.01–0.17, avg. 0.04), \(\hbox {Fe}_{2}\hbox {O}_{3}\) (0.01–1.94, avg. 0.47), MgO (0.01–0.47, avg. 0.15), CaO (0.04–0.14, avg. 0.09), \(\hbox {Na}_{2}\hbox {O}\) (0.02–1.31, avg. 0.09), \(\hbox {K}_{2}\hbox {O}\) (0.45–3.77, avg. 1.79) and \(\hbox {P}_{2}\hbox {O}_{5}\) (0.00–0.14, avg. 0.02; table 1). Gandikota Quartzites are also enriched in \(\hbox {SiO}_{2}\) (79.94–89.34, avg. 86.80) with lower contents of \(\hbox {Al}_{2}\hbox {O}_{3}\) (7.87–10.16, avg. 8.15), \(\hbox {TiO}_{2}\) (0.00–0.24, avg. 0.06), \(\hbox {Fe}_{2}\hbox {O}_{3}\) (0.01–5.36, avg. 0.89), MgO (0.01–2.60, avg. 0.36), CaO (0.04–0.45, avg. 0.10), \(\hbox {Na}_{2}\hbox {O}\) (0.02–1.11, avg. 0.42), \(\hbox {K}_{2}\hbox {O}\) (1.58–4.24, avg. 2.38) and \(\hbox {P}_{2}\hbox {O}_{5}\) (0.0–0.06, avg. 0.02; table 2). On the basis of \(\hbox {SiO}_{2}\) content, it has been suggested that the samples of the Pulivendla and Gandikota formations are quartz–rich to quartz-arenite type with the \(\hbox {SiO}_{2}\) content ranging from 76 to 95% (Condie 1993). The lower content of CaO and \(\hbox {Na}_{2}\hbox {O}\) (\(<1\%\)) is consistent with the lower proportion of the plagioclase. The \(\hbox {SiO}_{2}/\hbox {Al}_{2}\hbox {O}_{3}\) is \({>}\!10\), which indicates that sediments are highly mature. The \(\hbox {K}_{2}\hbox {O/Na}_{2}\hbox {O}\) ratio is \({\gg } 1\) in both these quartzites, which is consistent with the petrographic observations that the K-feldspar dominates over plagioclase feldspar. In the geochemical classification diagram proposed by Pettijohn et al. (1987), quartzite samples of Pulivendla and Gandikota plotted in the fields of arkose to sub-arkose, sub-litharenite to quartz arenite (figure 7a).

Fig. 6
figure 6

(a) Qt–F–L provenance ternary plot (after Dickinson 1985) of Pulivendla and Gandikota Quartzite. (b) QFL ternary diagram of quartzites (after Folk 1974).

Full size image

5.2 Trace element geochemistry

The chondrite normalised REE patterns of Pulivendla and Gandikota quartzites are characterized by LREE enriched with \(\hbox {La}_{\mathrm{N}}/\hbox {Sm}_{\mathrm{N}}\) ratios varying from 1.33 to 5.48 (avg. 3.23) and 1.05 to 6.91 (avg. 3.81), respectively. Both quartzites of Pulivendla and Gandikota are characterized by flat to slightly concave upward HREE patterns with \(\hbox {Gd}_{\mathrm{N}}/\hbox {Yb}_{\mathrm{N}}\) ratio varying from 0.47 to 1.87 (avg. 1.09) for Pulivendla and 0.46 to 2.16 (avg. 1.30) for Gandikota Quartzite with negative Eu (Pulivendla = avg. 0.15, Gandikota = avg. 0.61) anomaly. On the basis of the REE patterns and their \(\hbox {La}_{\mathrm{N}}/\hbox {Yb}_{\mathrm{N}}\) ratio, the Pulivendla quartzites have been divided into two groups. The first group samples are showing low LREE and high HREE, while second group is of quartzite is characterized by high LREE and low HREE. The enrichment of HREE in the first group of samples is attributed to the presence of zircon in the samples. Zircon preferentially incorporate HREE relative to LREE resulting in fractionated REE pattern with low \(\hbox {La}_{\mathrm{N}}/\hbox {Yb}_{\mathrm{N} }\) ratios. The Zr and Hf also show a good correlation with HREE which also shows that zircon is a source of REE. Second group of samples is characterised by high LREE and low HREE, which is due to the quartz dilution effect. The quartz dilution effect is also supported by having low \(\Sigma \)REE values as compared to the first group of quartzite (table 1). This indicates that samples of these formations were mainly derived from an old upper continental crust composed chiefly of felsic and intermediate source components (figure 8a and b).

Table 1 Major and trace element concentrations of Pulivendla Quartzites. Major oxides in wt%, trace and REEs in ppm. Normalising values of McDonough and Sun (1995).
Full size table
Fig. 7
figure 7

Sandstone classification diagram using log(\(\hbox {Na}_{2}\hbox {O/K}_{2}\hbox {O}\)) vs. log(\(\hbox {SiO}_{2}/\hbox {Al}_{2}\hbox {O}_{3}\)) (after Pettijohn et al. 1987).

Full size image
Fig. 8
figure 8

(a) Chondrite normalised REE pattern of Pulivendla Quartzite. (b) Chondrite normalised REE pattern of Gandikota Quartzite.

Full size image

The transition trace elements like Sc, V, Cr, Co and Ni also shows variable proportions in Pulivendla and Gandikota Quartzite. The quartzites of Pulivendla contain lower concentration of Sc (0.43–2.67, avg. 1.14), Cr (2.07–34.79, avg. 9.38) and Ni (2.64–27.34, avg. 7.91) with overlying Gandikota Quartzite (Sc = 0.55–4.46, avg. 1.46; Cr = 2.16–36.88, avg. 9.84; Ni = 3.76–22.06, avg. 9.81) and average higher content of V (3.19–20.75, avg. 11.25) than Gandikota Quartzite (V = 2.11–34.09, avg. 9.56; tables 1 and 2). Transition trace elements are highly enriched in clay minerals during weathering processes. There is a positive correlation of \(\hbox {Al}_{2}\hbox {O}_{3}\) with Cr (r = 0.13) and Ni (r = 0.20) of Chitravati Quartzite with very small negative correlation in Sc (r = –0.15) and V (r = –0.06), which suggest that these elements are more or less controlled by alumino silicate minerals and the nature of the source rocks. The positive correlation of the Ni with \(\hbox {Fe}_{2}\hbox {O}_{3}\) (r = 0.03) suggest possible association of Ni with Fe-oxide minerals.

The large ion lithophile elements (LILEs) are present in variable proportions in these quartzites. The Pulivendla Quartzites are characterized by similar Rb (2.01–80.79, avg. 16.16) and lower content of Sr (0.69–28.26, avg. 7.50), Ba (9.46–1127.62, avg. 165.50), Th (0.74–6.96, avg. 3.09) and U (0.28–2.37, avg. 0.97) compared to Gandikota Quartzite, Rb (1.16–91.06, avg. 11.54), Sr (2.32–260.61, avg. 43.36), Ba (4.72–1994.42, avg. 196.47), Th (1.03–20.57, avg. 4.90) and U (0.28–4.70, avg. 1.01; tables 1 and 2). In the potassium-rich minerals, like K-feldspar and biotite, Rb generally coexists with potassium, while Sr tends to enrich in Ca-bearing minerals (Dasch 1969). Relatively high values of Rb occur in Pulivendla Quartzite which again indicates dominance of K-feldspar bearing rocks in the source terrain. But in case of Gandikota Quartzite, they have higher proportion of Sr than Rb.

In terms of high field strength elements (HFSE), both the Pulivendla and Gandikota Quartzites contain low to high Zr (11.78–411.51, avg. 107.85, 19.01–1243.97, avg. 291.29, respectively) and low to moderate Hf values (0.13–5.72, avg. 1.87, 0.66–25.50, avg. 5.87, respectively; tables 1 and 2).

6 Discussion

6.1 Source area weathering

Lithologies that show different degrees of weathering in different environments like warm and humid climate are susceptible to chemical weathering, whereas cold and dry climate are susceptible to mechanical weathering. The intensity and period of weathering in clastic sedimentary rocks can be estimated by examining the association between alkali and alkaline elements (Nesbitt and Young 1996; Nesbitt et al. 1997). Nesbitt and Young (1982), defined the Chemical Index of Alteration (CIA) formulae to calculate the amount of chemical weathering

$$\begin{aligned} \hbox {CIA}= & {} [\hbox {Al}_{2}\hbox {O}_{3}/(\hbox {Al}_{2}\hbox {O}_{3}+ \hbox {CaO}\nonumber \\&+\hbox {Na}_{2}\hbox {O}+\hbox {K}_{2}\hbox {O})] \times 100. \end{aligned}$$
(1)

Oxides are in molar proportions and CaO represents the Ca in silicate fractions only. CIA values are of \(\sim \)50 for unweathered igneous rocks to near 100 for residual clays (initial 50–60, intermediate 60–80 and extreme \({>}80\); Nesbitt and Young 1982; Fedo et al. 1995). The CIA values in the Pulivendla Quartzite range from 41–80 (avg. 72) and Gandikota Quartzite 60–80 (avg. 71), respectively (tables 1 and 2), suggestive of low to moderate chemical weathering in the source area.

The CIA values are also plotted in \(\hbox {Al}_{2}\hbox {O}_{3}\)–(\(\hbox {CaO+Na}_{2}\hbox {O}\))–\(\hbox {K}_{2}\hbox {O}\) triangular plot (Nesbitt and Young 1984; Fedo et al. 1995; commonly referred as the ‘A–CN–K’ diagram) to categorize the provenance composition and weathering trends. The concept behind the use of this diagram is to understand the rate of weathering of plagioclase (Ca–Na feldspar) and K-feldspar (Middelburg et al. 1988). Thus, during weathering, CaO and \(\hbox {Na}_{2}\hbox {O}\) are preferentially leached relative to \(\hbox {K}_{2}\hbox {O}\) due to which the weathering trend moves parallel to the A–CN join. Intense weathering of a rock removes CaO, \(\hbox {Na}_{2}\hbox {O}\) and \(\hbox {K}_{2}\hbox {O}\), making the trend parallel to the A–K join.

The studied samples of the Pulivendla and Gandikota Quartzite are plotted in the A–CN–K ternary diagram in which majority of the samples are plotted above the feldspar tie line and few samples at right of the five trend line towards K-feldspar, which suggest that these samples might have suffered minor amount of K-metasomatism. To ascertain the presence or absence of post-depositional K-metasomatism, we have carried out petrographic and geochemical assessment of each sample. The higher content of \(\hbox {K}_{2}\hbox {O}\) and Rb in few samples and sericitization of plagioclase is also suggestive of post-depositional K-metasomatism (figure 9a). On the basis of weathering trends of the studied samples, it has been suggested that samples have undergone moderate to intense chemical weathering, which could be due to either differential weathering conditions or that the least weathered samples are representative of source rock.

Table 2 Major and trace element concentrations of Gandikota Quartzites. Major oxides in wt%, trace and REEs in ppm. Normalising values of McDonough and Sun (1995).
Full size table

Some indices utilize major oxides to try and acquire more complete scenarios for chemical modification during weathering processes. Mafic Index of Alteration (MIA) expands the condition of the CIA to incorporate the significant components of Mg and Fe (Babechuk et al. 2014). Considering the redox-subordinate weathering of Fe, the MIA index is coordinated into two forms for oxidative (MIA-O) and lessened (MIA-R) weathering. Meunier et al. (2013) further established this method by incorporating \(\hbox {SiO}_{2}\) into the index calculation and presented a weathering intensity scale (WIS). The WIS portrayed not only the Si-accumulation dominated kaolinization stage, but also the ultimate desilicification-dominated bauxitization/laterization stage for a general weathering procedure based on the co-variation between \(\hbox {R}^{3+}\)/(\(\hbox {R}^{3+}+\hbox {R}^{2+}+\hbox {M}^{+}\)) ratio and \(\Delta \)4Si% parameter (Yang et al. 2016). On the \(\hbox {R}^{3+}\)/(\(\hbox {R}^{3+}+\hbox {R}^{2+}+\hbox {M}^{+}\)) vs. \(\Delta \)4Si% diagram (Meunier et al. 2013; figure 9b), the studied sediments show the weathering trends from the felsic to mafic fields and intense chemical weathering. Furthermore, \(\hbox {M}^{+-}\hbox {4Si}\)–\(\hbox {R2}^{+}\) triangle diagram (Meunier et al. 2013; Yang et al. 2016; figure 9c) is used for the source rocks and weathering intensity of the source area. The majority of the studied sediments in this diagram plotted towards 4Si apex indicates intense weathering and source rocks from felsic to mafic.

Fig. 9
figure 9

(a) A–CN–K ternary diagram of molecular proportions of \(\hbox {Al}_{2}\hbox {O}_{3}\)–(\(\hbox {CaO}{+}\hbox {Na}_{2}\hbox {O}\))–\(\hbox {K}_{2}\hbox {O}\) for the Pulivendla and Gandikota Quartzite (after Nesbitt and Young 1984). (b) Chemiographic bases of the Weathering Alteration Scale (WIS). \(\hbox {M}^{+}\)–4Si–\(\hbox {R}^{2+}\) ternary plot (fields after Meunier et al. 2013; Yang et al. 2016). (c) \(\hbox {R}^{3+}/(\hbox {R}^{3+} + \hbox {R}^{2+} + \hbox {M}^{+})\) vs. \(\Delta \) 4Si% for sediments of Chitravati Group. Calculation of monocationic molar proportions (ex. Si = \(((\hbox {SiO}_{2}) \times 1000)/60.09\)), 4si = Si/4 (4Si% = 39.8% (average upper crust); \(\Delta \) 4Si% = (4Si% sample 39.8) \(\times 100/(100-39.8)\). Calculation of the \(\hbox {R}^{3+}\), \(\hbox {R}^{2+}\), and \(\hbox {M}^{+}\) parameters \(\hbox {R}^{3+}=\hbox {Al}^{3+}\)+ \(\hbox {Fe}^{3+}\); \(\hbox {R}^{2+}= \hbox {Mg}^{2+}\) + \(\hbox {Fe}^{2+}+\hbox {Mn}^{2+}\); \(\hbox {M}^{+}= \hbox {Na}^{+}+ \hbox {K}^{+}+\hbox {2Ca}^{2+ }\)(fields after Meunier et al. 2013). (d) Two weathering indicators, Index of Chemical Variation (ICV) vs. Chemical Index of Alteration (CIA; fields after Potter et al. 2005).

Full size image

Chemical Index of Weathering (CIW) of Harnois (1988) is also used to assess intensity of chemical weathering. It is considered as a better index than CIA because it does not include \(\hbox {K}_{2}\hbox {O}\) content and thus eliminate the possibility of K-metasomatism. It is calculated as:

$$\begin{aligned} \hbox {CIW}= [\hbox {Al}_{2}\hbox {O}_{3}/ \hbox {Al}_{2}\hbox {O}_{3} +\hbox {CaO}{*}+\hbox {Na}_{2}\hbox {O}] \times 100\qquad \end{aligned}$$
(2)

CIW values of the studied Pulivendla and Gandikota Quartzite range from 49.85 to 97.59 (avg. 91.21) and 80.44 to 97.60 (avg. 90.87), respectively. CIW indices are higher than CIA values for some analysed samples due to exclusion of \(\hbox {K}_{2}\hbox {O}\) from the index. On the basis of CIW, the studied sediments also show moderate to intense weathering.

One more fine evaluation method to determine the amount of chemical weathering is Plagioclase Index of Alteration (PIA; Fedo et al. 1995), which can be considered by the subsequent equation. In this, all oxides are expressed in molecular proportions

$$\begin{aligned} \hbox {PIA}= & {} [(\hbox {Al}_{2}\hbox {O}_{3}- \hbox {K}_{2}\hbox {O})/ (\hbox {Al}_{2}\hbox {O}_{3} + \hbox {CaO}\nonumber \\&+\, \hbox {Na}_{2}\hbox {O}- \hbox {K}_{2}\hbox {O})] \times 100 \end{aligned}$$
(3)

PIA values of \(\sim \)50 for fresh rocks and values similar to 100 designate considerable productions of secondary aluminous clay minerals (Fedo et al. 1997). The PIA value of Pulivendla Quartzite is 37–96 (avg. 87) and Gandikota Quartzite is 70–96 (avg. 86). Like CIA, A–CN–K ternary diagram and CIW, the range of PIA values of all these quartzites also suggest moderate to intense chemical weathering.

The Index of Chemical Variability (ICV) can also be useful as an index for recycling and compositional maturity in sedimentary rocks (Cox et al. 1995; Armstrong-Altrin 2015)

$$\begin{aligned} \hbox {ICV}= & {} (\hbox {Fe}_{2}\hbox {O}_{3} +\hbox {K}_{2}\hbox {O}+ \hbox {Na}_{2}\hbox {O}+\hbox {CaO}\nonumber \\&+\hbox {MgO}+\hbox {MnO}+\hbox {TiO}_{2})/\hbox {Al}_{2}\hbox {O}_{3} \end{aligned}$$
(4)

ICV values of Pulivendla Quartzite range from 0.30 to 1.76 (avg. 0.57) reflect the high mature sediments recycled. The high ICV value (\(\sim \)1) reflects that the sediments were deposited as first cycle deposits in tectonically active continental margins. But Gandikota Quartzite are having the ICV range from 0.27 to 1.29 (avg. 0.69). The samples with ICV \({<}1\) are showing the signature of sediment recycling and highly mature. The samples with ICV \({>}1\) are indicating that these are first cycle of sediments and immature nature (table 2).

Similarly, the ICV vs. CIA plot (figure 9d, after Potter et al. 2005; LaMaskin et al. 2008; Absar and Sreenivas 2015) suggest that the source of the studied sediments is from predominantly granodiorite source rocks. However, some samples fall along the granite and basalt mixing line, indicating mixed igneous provenance. Virtually weak and non-enduring weathering condition in the source ranges are shown by the substantial inconstancy of CIA esteems and variable convergence of labile components, for example, Ca, Na, and Sr (Nesbitt et al. 1997). In this distinctive circumstance, we derive that these sediments were provided from a quickly uplifted source zone.

On the basis of the weathering indices like CIA, A–CN–K plot (figure 9a), CIW (Harnois 1988), PIA and ICV, ICV vs. CIA plot (figure 9d) of Pulivendla and Gandikota Quartzite, it has been suggested that these sediments suffered moderate to intense chemical weathering and are deposited in humid and warm climate. The low to moderate chemical weathering of these sediments is due to nonsteady state weathering conditions where active tectonism and uplift allow erosion of all soil horizons and rock surfaces (Nesbitt et al. 1997). Low to moderate chemical weathering in the quartzites of Pulivendla and Gandikota reflects high erosion rate giving less time to the debris to stay in situ.

Hydraulic sorting preserves the chemical composition of terrigenous sedimentary rocks and also dominantly controls the distribution of various trace elements (e.g., Th, U, Zr, Hf and Nb) (Etemad-Saeed et al. 2011). McLennan et al. (1993) used Th/Sc vs. Zr/Sc plot to discriminate the effects of source composition and sedimentary processes on the final composition of clastic sedimentary rocks. On the Th/Sc vs. Zr/Sc binary plot for quartzites two trends are observed, one showing a direct contribution from primary source rocks, and the other revealing the influence of edimentary recycling (figure 10a). These sediments are enriched in heavy minerals particularly zircon due to sediment sorting and recycling. Similarly, these samples plot in the field of sub-parallel to trend one near the Proterozoic sandstones (Condie 1993) suggesting compositional heterogeneity and maximum influence of sorting and recycling by heavy minerals. Further, Th/U ratios of 3.5–4.0 in Th/U vs. Th plot indicates that the sediments are derived from upper crustal igneous rocks and if the Th/U ratios are below 3.5, they are supposed to have been derived from depleted mantle. Our quartzite samples from Pulivendla and Gandikota reflect both the components. During the continuous sedimentary processes, lower Th/U ratios are usually the result of U enrichments found in active margin sediments, throughout the post-Archean terranes (McLennan et al. 1993). During the post-Archean, low Th/U ratios are likely to be a sign of origin of crustal precursors from depleted mantle sources. This is reflected in our samples (figure 10b).

Fig. 10
figure 10

(a) Th/Sc vs. Zr/Sc diagram for Pulivendla and Gandikota Quartzite (McLennan et al. 1993). The accumulation of zircon due to sediment recycling and sorting is observed in trend 2 and compositional variation in trend 1. (b) Plot of Th/U vs. Th showing majority of samples low values of Th \({<}10\) and low Th/U ratio above four suggested upper crustal regions (after McLennan et al. 1993).

Full size image
Fig. 11
figure 11

(a) Eu/Eu* vs. \(\hbox {Gd}_{ \mathrm{N}} /\hbox {Yb}_{ \mathrm{N}}\) plot showing all of our studied samples plotted in post-Archean field. (b) Th/Sc vs. Cr/Th plot (after Totten et al. 2000).

Full size image
Table 3 REE mixing calculations taking all averages 70% Tadpatri shale (A) + 30% Quartzite (B) as a sample and 40% Granitoid (G) + 40% Closepet granite (CG) + 20% Basalt (B) as a model.
Full size table

6.2 Provenance

The chemical composition of sedimentary rocks is controlled by a complex suite of parameters operating through erosion, transport and deposition. The principal first-order parameters include source rock composition, modification by chemical weathering, mechanical disaggregation and abrasion, authigenic inputs, hydraulic sorting, and diagenesis (Johnsson 1993; Walsh et al. 2016). For example, alkali and alkaline earth elements, such as K, Na, Ca and Sr may be transported as dissolved species and their abundances in sedimentary rocks may not reflect their abundances in source terrain (Sheldon et al. 2002). However, immobile elements such as Al\(_{2}\)O\(_{3}\), Ti, Th, Ni, Cr, Co, Zr and REE are commonly transported in solid detritus and are reliable indicator of provenance (Holland 1978; Chaudhuri and Cullers 1979; Taylor and McLennan 1985; Totten and Blatt 1993). For the purpose of identification of the provenance, various major and trace element ratios like \(\hbox {Al}_{2}\hbox {O}_{3}/\hbox {TiO}_{2}\), Th/Sc, La/Sc, La/Co, Co/Th, Cr/Th and Cr/Zr of the siliciclastic rocks are reliable provenance indicators (Bhatia and Crook 1986; Bauluz Lazaro et al. 1995; Cullers and Berendsen 1998). The \(\hbox {Al}_{2}\hbox {O}_{3}\)/\(\hbox {TiO}_{2}\) for the felsic rocks is generally ranging from 10 to 100 (sometimes higher), whereas for mafic rocks it is \({<}20\) (Hayashi et al. 1997). The \(\hbox {Al}_{2}\hbox {O}_{3}\)/\(\hbox {TiO}_{2}\) ratio of the Pulivendla Quartzite (27.5–826.0, avg. 339.9) and Gandikota Quartzite (6.33–831.0, avg. 215), which suggest that sediments are derived dominantly from felsic source with minor proportion from mafic or ultramafic source rocks. Cullers and Podkovyrov (2000) suggested various trace element ratios for coarse and fine grained rocks for the provenance purpose. Coarse grained sediments have Th/Sc range for felsic rocks 0.84 to 20.5 and for basic rocks 0.05 to 0.22 and La/Sc ratio for felsic rocks 2.5 to 16.3 and for basic rocks 0.43 to 0.86. Coarse grained sediments derived from felsic sources have Th/Cr values ranging from 0.13 to 2.7 and basic rock 0.018 to 0.046 (Cullers and Podkovyrov 2000 and references therein). The trace element ratios of Pulivendla Quartzite are Th/Sc (0.74–6.33, avg. 2.84), La/Sc (0.79–12.83, avg. 4.44), Th/Cr (0.02–1.44, avg. 0.63) and V/Ni (0.47–5.65, avg. 1.98) and for Gandikota Quartzite are Th/Sc (0.84–7.36, avg. 3.45), La/Sc (1.04–6.27, avg. 3.32), Th/Cr (0.05–4.05, avg. 1.0) and V/Ni (0.13–5.74, avg. 1.35). On the basis of these trace element ratios of Pulivendla and Gandikota Quartzite, we are inferring here that sediments of Pulivendla and Gandikota Quartzite-are derived dominantly from felsic source with minor contribution from mafic source.

Fig. 12
figure 12

(a) La/Th vs. Hf diagram of source rock discrimination for the discussion of the clastic sediments and their compositions reflects the mixed felsic-mafic source. (b) Chondrite-normalized REE patterns of average Chitravati Group siliciclastics compared with models after mixing the end-members in the proportion of 40% G: 40% CG: 20% B. Granitoids (G; Dey et al. 2014), Closepet Granite (CG; Moyen et al. 2001) and Basalt (B; Manikyamba et al. 2004).

Full size image

Furthermore the quartzites of Pulivendla and Gandikota have negative Eu/Eu* (Pulivendla: 0.09–0.21, avg. 0.15; Gandikota: 0.46–0.72, avg. 0.61) with high \(\hbox {La}_{\mathrm{N}}/\hbox {Yb}_{\mathrm{N}}\) ratio (0.71–16.63, avg. 5.36, for Pulivendla; 2.56–17.23, avg. 8.09, for Gandikota). Felsic rocks generally have negative Eu anomaly and high \(\hbox {La}_{\mathrm{N}}/\hbox {Yb}_{\mathrm{N}}\) ratios, whereas mafic rocks have low \(\hbox {La}_{\mathrm{N}}/\hbox {Yb}_{\mathrm{N}}\) ratios (McLennan et al. 1990). In the chondrite normalised REE patterns of both quartzites showing LREE enriched with flat HREE and few samples with concave upward HREE patterns (figure 8a and b). The REE patterns and their ratios of our samples also suggest a heterogeneous source comprising felsic dominant component with minor proportion of mafic component.

The \(\hbox {Gd}_{\mathrm{N}}/\hbox {Yb}_{\mathrm{N}}\) ratio also document the nature of source rocks and the composition of the continental crust (Taylor and McLennan 1985; Nagarajan et al. 2007). On Eu/Eu* vs. \(\hbox {Gd}_{\mathrm{N}}/\hbox {Yb}_{\mathrm{N}}\) diagram (figure 11a, fields after McLennan et al. 1993), all our samples plot in post-Archean field, near to PAAS values. The studied sediments are also plotted in Cr/Th vs. Th/Sc plot (Totten et al. 2000; figure 11b) and La/Th vs. Hf (Floyd and Leveridge 1987) in which samples showing mixed provenance (figure 12a) source.

The provenance modelling using chondrite normalised REEs have been established to be a valuable tool for determining the contribution of possible end-members to the sedimentary basin (e.g., Hofmann 2005; Roddaz et al. 2007). In this provenance modelling it is necessary that mass balance should be taken into consideration. It is known that pelitic rocks (shale) and sandstone include 70 and 30%, respectively of the total mass of sediments (Mackenzie and Garrels 1971; Taylor and McLennan 1985), consequently a mixture of 70% shale and 30% sandstone is taken as model composition. Shale unit from Tadpatri Formation (Ramavathi Mathur et al. 1995), which is the Chitravati Group is used for mixing model. Components of the Dharwar craton like Granitoids (G; Dey et al. 2014), Closepet Granite (CG; Moyen et al. 2001) and Basalt (B; Manikyamba et al. 2004) have been taken as end members for the function of modelling of Chitravati Group. The mixing calculations from these end members suggest a possible model for Chitravati siliciclastics in the proportions of 40% G: 40% CG: 20% B (table 3). The chondrite normalised REE patterns and their ratios are near matching to those of average sediments of Chitravati siliciclastics (figure 12b) and are in agreement with presently exposed proportion of the end-members of the respective sources. Even though this mixing model does not yield an exceptional solution, it positively specifies contribution of source terrain rare earth element abundance for the genesis of sedimentary rocks of the Chitravati Group.

Fig. 13
figure 13

(a) Discrimination function plot of the Pulivendla, Gandikota Quartzite (fields after Bhatia 1983). Discriminant function \(1\, (\hbox {DF}1) = -0.0447 \hbox {SiO}_{2} - 0.972 \hbox {TiO}_{2} + 0.008 \hbox {Al}_{2}\hbox {O}_{3} - 0.267 \hbox {Fe2O}_{3} + 0.208 \hbox {FeO} - 3.082 \hbox {MnO}+0.140 \hbox {MgO} + 0.195 \hbox {CaO} + 0.719 \hbox {Na}_{2}\hbox {O} - 0.032 \hbox {K}_{2}\hbox {O} + 7.510 \hbox {P}_{2}\hbox {O}5 + 0.303\). Discriminant function 2 \((\hbox {DF}2) = -0.421 \hbox {SiO}_{2 }+ 1.988 \hbox {TiO}_{2} - 0.526 \hbox {Al}_{2}\hbox {O}_{3}- 0.551 \hbox {Fe}_{2}\hbox {O}_{3} - 1.610 \hbox {FeO} + 2.720 \hbox {MnO}+0.881 \hbox {MgO} -0.907 \hbox {CaO}- 0.177 \hbox {Na}_{2}\hbox {O} - 1.840 \hbox {K}_{2}\hbox {O} + 7.244 \hbox {P}_{2}\hbox {O}_{5} + 43.57\). (b) Discriminant function multidimensional diagram for high-silica clastic sediments (Verma and Armstrong-Altrin 2013). The discriminant function equations are: \(\hbox {DF1(Arc-Rift-Col)} = (-0.263 \times \hbox {ln}(\hbox {TiO}_{2}/\hbox {SiO}_{2})\hbox {adj}) + (0.604 \times \hbox {ln} (\hbox {Al}_{2}\hbox {O}_{3}/\hbox {SiO}_{2})\hbox {adj}) + (-1.725 \times \hbox {ln} (\hbox {Fe}_{2}\hbox {O}_{3}\hbox {t/SiO}_{2})\hbox {adj}) + (0.660 \times \hbox {ln}(\hbox {MnO/SiO}_{2})\hbox {adj}) + (2.191 \times \hbox {ln}(\hbox {MgO/SiO}_{2})\hbox {adj}) + (0.144 \times \hbox {ln}(\hbox {CaO/SiO}_{2})\hbox {adj}) + (-1.304 \times \hbox {ln}(\hbox {Na}_{2}\hbox {O/SiO}_{2})\hbox {adj}) +(0.054 \times \hbox {ln}(\hbox {K}_{2}\hbox {O/SiO}_{2})\hbox {adj}) + (-0.330 \times \hbox {ln}(\hbox {P}_{2}\hbox {O}_{5}/\hbox {SiO}_{2})\hbox {adj}) + 1.588\). \(\hbox {DF2(Arc-Rift-Col)} = (-1.196 \times \hbox {ln(TiO2/SiO2)adj)} + (1.604 \times \hbox {ln}(\hbox {Al}_{2}\hbox {O}_{3}/\hbox {SiO}_{2})\hbox {adj}) + (0.303 \times \hbox {ln}(\hbox {Fe}_{2}\hbox {O}_{3}\hbox {t/SiO}_{2})\hbox {adj}) + (0.436 \times \hbox {ln}(\hbox {MnO/SiO}_{2})\hbox {adj}) + (0.838 \times \hbox {ln}(\hbox {MgO/SiO}_{2})\hbox {adj}) + (-0.407 \times \hbox {ln}(\hbox {CaO/SiO}_{2})\hbox {adj})+ (1.021 \times \hbox {ln}(\hbox {Na}_{2}\hbox {O/SiO}_{2})\hbox {adj}) + (-1.706 \times \hbox {ln}(\hbox {K}_{2}\hbox {O/SiO}_{2})\hbox {adj}) +(-0.126 \times \hbox {ln}(\hbox {P}_{2}\hbox {O}_{5}/\hbox {SiO}_{2})\hbox {adj}) - 1.068\). (c) Plots of major oxide data in the different tectonic setting discrimination diagrams. Plot of (\(\hbox {Fe}_{2}\hbox {O}_{3}+\hbox {MgO}\)) vs. \(\hbox {TiO}_{2 }\) content (fields after Bhatia 1983). (d) Plot of (\(\hbox {Fe}_{2}\hbox {O}_{3}+\hbox {MgO}\)) vs. (\(\hbox {Al}_{2}\hbox {O}_{3}/\hbox {SiO}_{2})\) (after Bhatia 1983). Note that the majority of the sample plots are close to the passive margin field.

Full size image

Geochronological studies on Chitravati Group are showing the \(1923\pm 22\,\hbox {Ma}\) (Collins et al. 2015) as a consistent maximum depositional age for the Pulivendla Formation. This information is in agreement with the present geochemical studies, which infer Dharwar cratonic rocks as a Provenance for the Pulivendla Formation. The Gandikota Formation yields the maximum depositional age of \(1181{\pm } 29\,\hbox {Ma}\) (Collins et al. 2015) and the provenance was inferred to be the Krishna orogeny (Collins et al. 2015). The Paleocurrent analysis (Nagaraja Rao 1974; Lakshminarayana and Bhattacharjee 2000) is supporting the Dharwar cratonic rocks as a Provenance. The bi-modal Paleocurrent directions noticed by Lakshminarayana and Bhattacharjee (2000) indicate the provenance of the Gandikota Formation should be two directional of which one direction supports geochronological evidence (Collins et al. 2015; \(1181{\pm } 29\,\hbox {Ma}\)), i.e., sediments were also derived from Krishna orogeny and the other paleocurrent direction was supporting the Dharwar craton source. Our petrological, geochemical and provenance modelling studies show that the Gandikota Quartzite were derived from a mixed component source involving both Dharwar and Krishna Orogeny (by earlier isotopic studies by Collins et al. 2015).

6.3 Tectonic setting

Sediments derived from different tectonic settings vary in different geochemical characteristics. Major and trace-element and their different bivariate and multivariate diagrams with discrimination functions are predominantly valid for tectonic setting of the sedimentary basins (Bhatia 1983; Roser and Korsch 1986). Major element discrimination function diagram of Bhatia (1983) for the studied samples of Pulivendla and Gandikota Quartzite are showing passive to active continental margin setting (figure 13a).

Recently, Verma and Armstrong-Altrin (2013) proposed two discriminant function diagrams based on major elements for the tectonic discrimination of low and high silica rich sediments. In these diagrams there are three major different tectonic setting fields, viz., continental arc (island arc), continental rift and collision. Present studied samples are all high-silica sediments, which are plotted in the rift and collisional fields of discriminant function multidimensional diagram of Verma and Armstrong-Altrin (2013; figure 13b).

Similarly, the plot of \(\hbox {Fe}_{2}\hbox {O}_{3}{+}\hbox {MgO}\) vs. \(\hbox {TiO}_{2 }\) (figure 13c; Bhatia 1983; Basu et al. 2016); \(\hbox {Fe}_{2}\hbox {O}_{3}+\hbox {MgO} \, { vs.} \, \hbox {Al}_{2}\hbox {O}_{3}/\hbox {SiO}_{2}\) (figure 13d; Bhatia 1983), tectonic setting diagram reflecting the both of the studied sediments are plotted in passive margin setting except four samples of Gandikota Quartzite showing active continental margin settings. Corroborating with major element data, the trace element ternary diagram Th–Sc–Zr/10 of the studied samples of Pulivendla and Gandikota, is showing passive to active tectonic setting (figure 14).

Fig. 14
figure 14

Th–Sc–Zr/10 ternary diagram for Pulivendla and Gandikota Quartzite of Chitravati Group (after Bhatia and Crook 1986).

Full size image

7 Conclusions

  1. 1.

    On the basis of petrography and ICV the quartzites of Chitravati Group are mostly well sorted, texturally and compositionally mature. The CIA, PIA, CIW, WIS and ACNK ternary diagram suggests that these quartzites have undergone moderate to intense chemical weathering in their source area.

  2. 2.

    Discrimination function diagrams and ternary diagram show passive to active continental margin setting in conjunction with contemporaneous volcanism and sedimentation.

  3. 3.

    Based on geochemical provenance modelling studies of Chitravati Group quartzites (Cuddapah Supergroup), it is suggested that granitoid terrains to the north, west and south of the Cuddapah basin are the source of these quartzites as suggested by earlier workers.